Offshore structure with rotating and indexing mechanism for placing piles

ABSTRACT

An offshore structure having a base resting on a sea floor, a plurality of vertical pile-receiving sleeves in the base, an elongated rigid vertical member joined to the base by a connection which permits angular pivotal displacement and rotation of the vertical member, and at least one vertical pileguiding means positioned on the vertical member to be axially alignable with a plurality of the vertical pile-receiving sleeves on an individual sleeve basis upon rotation of the vertical member about its vertical axis.

United States Pate Kouka I Sept. 4, 1973 [54] OFFSHORE STRUCTURE WITHROTATING 3,522,709 8/1970 Vilain 61/465 AND INDEXING MECHANKSM FOR3,572,044 3/1971 Pogonowski... 61/465 3,643,446 2/1972 Mott 61/465PLACING PILES [75] Inventor: Frederick Horace Kouka, Western Springs,Ill.

[73] Assignee: Chicago Bridge 81. Iron Company,

Oak Brook, ll].

Filed: Nov. 12, 1971 Appl. No.: 198,341

US. Cl ..61/46.5, 61/50, 61/535 Int. Cl E02b 17/00, B63b 35/44 Field ofSearch 61/46, 53.5, 46.5,

[56] References Cited UNITED STATES PATENTS 3,474,630 10/1969 Pogonowski61/465 Primary Examiner-Jacob Shapiro Attorney-Charles J. Merriam,Jerome B. Klose et al.

[57] ABSTRACT 9 Claims, 7 Drawing Figures PATENTEDsEP 41915 3756053$HEEI 2 0F 2 OFFSHORE STRUCTURE WITH ROTATING AND INDEXING MECHANISM FORPLACING PILES This invention relates to offshore structures such as areused for the exploration and production of oil, as well as for shipmoorings and other purposes.

In the production and exploration for oil offshore, it is quite commonto use structures which rest on the sea floor. Such structures can beused for well drilling and also for use in producing oil after it isfound. Various types of offshore structures have been developed and arein use for such purposes. Most such structures however are only suitablefor use in relatively shallow water such as up to about 250 feet indepth.'0ffshore structures for use in deeper water generally must bedesigned differently than those used in shallow water.

alignable with a plurality of the vertical pile-receiving sleeves, on anindividual sleeve basis, upon rotation of the vertical member about itsvertical axis. The offshore structure also advisably includes means toalign and position the pile-guiding means axially to pilereceivingsleeves on an individual sleeve basis. The pile-receiving sleeves areadvisably positioned an equal distance radially from the mechanicalconnection means or, in other words, more or less in a circulararrangement in the base or foundation structure. Furthermore, thepile-guiding means is also positioned the same distance radially fromthe mechanical connection means as are the pile-receiving sleeves.

The invention also provides a method of securing such an offshorestructure to a sea floor by piles. The

. described structure is employed in such method. In per- Chamberlin etal. U.S. Pat. No. 3,553,969 discloses an I offshore structure for use indeep water. That structure comprises a base or foundation which rests ona sea floor and a vertlcal shaft or tube which is connected at its lowerend by a pivotal connection, such as a universal joint, to the base orfoundation. The shaft or tube extends upright to above sea level and hassufficient buoyancy to maintain it in an upright, vertical position whenno significant wind or sea forces are applied to it. When sea or windforces are applied, it pivots angularly from its pivot connection at itslower end but the tilting is not excessive because of the buoyancy whichthe shaft possesses.

The offshore structure of the type shown in Chamberlin et al isconsidered to have wide usefulness. However, to be suitably employed indeep water, it is necessary that the base or foundation be well securedto the sea floor by means of piles. The implacement of piles in deepwater is most difficult as well as expensive. Even when the base orfoundation is previously provided with suitable pile-receiving sleevesor tubes, it is time consuming and troublesome to direct a pile from thesea surface into such a pile-receiving sleeve. It is difficult to makealingment and, even when alignment is achieved, it is often lost throughaction of wave and sea currents before the pile can be threaded orslipped into the pile-receiving sleeve. It is accordingly necessary inmany instances to employ the services ofa deep sea diver to properlyposition the pile. Deep sea divers however cannot actively work in deepwater for more than one-half to one hour without emerging for anextended period. Furthermore, they must employ special equipmentincluding the use of a breathing system which employs unique gasmixtures such as oxygen and helium. It is thereforebelieved clear thatthere is a great need for means to facilitate the installation of pilesinto the base or foundation 'of an offshore structure, paricularly ofthe type shown in Chamberlin et al.

According to the present invention there is provided an offshorestructure adapted to be supported on a sea floor comprising a baseadapted to rest on a sea floor, a plurality of substantialy hollowvertical pile-receiving sleeves in the base for receiving piles to bedriven into the sea floor, an elongated rigid normally substantiallyvertical member joined to the base by a mechanical connection meanswhich permits angular pivotal displacement of the vertical member aboutsaid connection, said connection permitting rotation of the verticalmember about the axis of said vertical member, and said vertical memberhaving at least one vertical pileguiding means positioned thereon whichis axially forming the method, a pile is placed in the pile-guidingmeansand by means of such guide it is fed into a pilereceiving sleeve.The pile is then driven into the sea floor. After that the verticalmember is rotated until the pile-guiding means is in alignment with asecond pilereceiving sleeve. A pile is then placed in the pileguidingmeans and fed by it into a second pile-receiving sleeve following whichthe pile is driven into the sea floor. This procedure is repeated untilthe piles are driven into the sea floor. The piles can be grouted orcemented to the base or foundation after the driving of each iscompleted or after a plurality of all of the piles have been driven intothe sea floor.

The invention will now be described further in conjunction with theattached drawings in which:

FIG. 1 is an elevational view of an offshore structure providedaccording to the invention;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is an expanded view of the mechanical connection member elements;

FIG. 5 is a plan view of the trunnion block of the mechanical connectionshown in FIG. 4;

FIG. 6 is a vertical sectional view of the telescoping tubular membersof the mechanical connection of FIG. 4 which holds the mechanicalconnection together while permitting rotation and indexing of thepileguiding means with the pile-receiving sleeves; and

FIG. 7 is a diagrammatical sectional view taken along the line 7--7 ofFIG. 1 and shows thrusters for rotating the structure.

So far as is practical, the various parts and elements which appear inthe different views of the drawings will be identified by the samenumbers.

With reference to FIGS. 1 to 3, the offshore structure 10 has a base orfoundation 11, a vertical member 12 and a mechanical connection 13 atthe lower end of the vertical member which joins it to the base 11.

Base 11 comprises a toroidal member 14 which is joined to a verticalcylindrical centrally located supporting post member 15 by a purality ofspokes 16. A plurality of pile-receiving sleeves 17 are verticallypositioned in toroidal member 14. Normally there will be far morepile-receiving sleeves than are shown in FIGS. 1 to 3 but, for purposesof clarity, only a limited number thereof have been shown in thedrawings. The spokes 16 are shown in FIG. 1 to be inclined at an angle.It should be understood that additional horizontal spokes extend frommember 14 to the central post 15 to further strengthen the structure.Furthermore, the base as illustrated by FIGS. 1 to 3 is onlyrepresentative of bases or foundations which can be employed in theoffshore structure. Other shapes and designs can be used for the baseprovided they have the necessary pilereceiving sleeves and means forjoining with, or receiving, a mechanical connection which permits thedesired angular movement or displacement and axial rotation of verticalmember 12.

The vertical member 12, as shown in FIGS. 1 and 3, has four verticalhollow tubes 21. Each of the tubes 21 extends through a buoyancytank 22positioned around the upper end of each tube. Horizontal braces 23 joinadjacent tubes 21 and adjacent floatation tanks 22 together. Diagonalbraces 24 also extend from adjacent tubular members 21 and adjacentfloatation tanks 22 and are joined thereto to reinforce the entirevertical member 12 and thereby form a truss-like structure. Tank 25 islocated in the lower or bottom portion of vertical member 12 to providea means for applying ballast to the bottom part of the vertical memberto thereby obtain a structure having a center of gravity such that thevertical member 12 will normally be upright when the structure is inwater. Tank 25 is held in position by means of braces 26 and downwardlyextending spokes 27 (FIGS. 1 and 4). On top of vertical member 12 thereis positioned a platform 28 which can be used as desired. It is locatedto be above wave action of the sea.

The mechanical connection 13 which joins the vertical member 12 to thebase 11 is shown in greater detail in FIGS. 4 to 6. With reference toFIGS. 4 and 5, trunnion block 31 has opposing trunnions 32 and 33, andat right angle thereto it has opposing trunnions 34 and 35. Trunnions 32and 33 rest in bearing blocks provided in supporting member 36 which isheld in fixed position by welding it to the ends of diagonal spokes 16.Bearing elements 37 and 38 are employed to secure trunnions 32 and 33respectively to supporting member 36 in a manner which permits axialrotation of the trunnion block 31 by means of trunnions 32 and 33. Uppersupporting member 39 has a pair of spaced-apart opposing bearing blocks40 which receive trunnions 34 and 35, and such trunnions are held inplace by a pair of bearing elements 41. The resulting mechanicalconnection is auniversal joint which permits member 39, and any elementattached thereto, to be angularly displaced.

The upper supporting member 39 is provided with base plate 41 and aspacing, retaining ring 42. The upper supporting member 39 is ofgenerally tubular shape and telescopes inside of tubular cylindricalrotatable member 43. The ends of diagonally located spokes 27 are weldedto rotatable member 43 to secure it to the bottom portion of verticalmember 12. Guide and spacing rings 44 and 45 are positioned on theinside wall of rotatable member 43. A contact plate 46 is positionedalong the lower outer edge of rotatable member 43 and it has a pluralityof slots in the perimeter thereof to receive pawls 47 and 48 which arepivotably joined at their upper ends to rotatable member 43. Cables 49and 50 are joined to pawls 47 and 48 respectively and extend to platform28 to raise the pawls from such slots to disengage them from plate 41 aswill be subsequently further explained. Suitable mechanical means suchas a pneumatic or hydraulic actuated rams can be used in place of cables49 and 50 to raise and lower the pawls.

Member 39 is telescoped into rotatable member 43 until plate 46 contactsplate 41 as shown in the sectional view of FIG. 6. The two half-circlerings 51 and 52 (FIGS. 4 and 6) are then bolted to the inside lowersurface of rotatable member 43 at a location below spacer ring 42 onmember 39. When an upward force is applied to member 43, the half circlerings 51 and 52 come into contact with ring 42 and thereby preventfurther upward movement thereof.

Appropriate slots are provided in plate 41 to receive pawls 47 and 48when at least one of the vertical tubular members 21 is axially alignedwith at least one of the pile-receiving sleeves 17. When alignment isthereby effected, a pile threaded through tubular member 21 will beguided and directed into a pile-receiving sleeve without any additionalmeans being required for such orientation. Of course, the pile-receivingsleeves 17 can be so spaced as to have two or more of the verticaltubular elements 21 aligned with respective pilereceiving sleeves 17 atany one time when the pawls are positioned in receiving slots in plate41. For such an arrangement vertical tubular elements 21 are positionedradially from the vertical axis of vertical member 12 at a distancesubstantially equal to the radial distance that the pile-receivingsleeves 17 are located from the vertical axis of the base or foundation11. Such radial distance can conveniently be measured from the centralaxis of the mechanical connection means which, in the case asillustrated, is a universal joint.

FIG. 1 illustrates a pile 60 which has been driven into the sea floorand then cut-off from an upper pile extension 61. Pile 60 can then begrouted or cemented in the pile-receiving sleeve. Pile 62 (FIG. 1) is inprocess of being driven into the sea floor. After it has been driven tothe desired depth it can be cut off above the pilereceiving sleeve 17.Then vertical member 12 can be rotated, after first raising pawls 47 and48 from slots in plate 41, by any suitable means. When pawls 47 and 48again fall into slots in plate 41, at least one of tubular members 21 isagain in alignment with a pile-receiving sleeve 17. Another pile is thenthreaded through the tubular member 21 into a sleeve 17 and is thendriven into the sea floor. Driving the piles can be effected fromplatform 28 above sea level. This operation is repeated until the pilesare driven into place and grouted.

FIG. 7 shows a means of rotating vertical member 12 although othercommon means, such as a tugboat, can be used. Electric poweredreversible-propeller thrusters 62, previously known in the art and notclaimed herein, can be mounted on two opposing buoyancy tanks 22 toprovide the desired rotation of vertical member 12.

After all the piles are driven into place, or earlier if only some ofthe piles are to be driven into place using the described system, thetelescoping members 39 and 43 are secured together, such as by means ofgrout, to prevent further rotation of. vertical member 12 about itsvertical axis.

Although members 21 are shown as tubes or pipes, they can also betrough-like members with suitable bands Other to provide guide means forthe piles. dother structures can also obviously be used to guide thepiles to thread them into the pile-receiving sleeves so that it is notintended to limit the invention to any one particular structure suitablefor this purpose.

While the mechanical connection 13 shown in the drawings is a universaljoint, it is not intended to limit the invention to such a structuresince a ball and socket or other mechanically equivalent connection canbe used which permits angular deflection or displacement of verticalmember 12 when the sea and wind forces are applied thereto.

Cutting of the piles above the top of the sleeves may be unnecessary ifpiling of suitable lengths are employed and connected end-to-end byreleasable connections. After the pile 'has been driven to a depth whichplaces such a connection above the top of a sleeve the connection can bereleased and a new length of piling added to the top to ready theapparatus for driving a pile in a different sleeve.

The foregoing detailed description has been given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom as modifications will be obvious to those skilled in the art.

What is claimed is:

1. An offshore structure adapted to be supported on a sea floorcomprising:

a base adapted to rest on a sea floor;

a plurality of substantially hollow vertical pilereceiving sleeves inthe base for receiving piles driven into the sea floor;

an elongated rigid normally substantially vertical member joined to thebase by a mechanical connection having means for angular pivotaldisplacement of the vertical member about said connection, saidconnection having means for rotation of the vertical member about theaxis of said vertical member; and

the vertical member having at least one vertical pileguiding meanspositioned thereon to be axially alignable with a plurality of thevertical pilereceiving sleeves on an individual sleeve basis uponrotation of the vertical member about its vertical axis.

2. An offshore structure according to claim 1 having index means toalign and position the pile-guiding means axially to pile-receivingsleeves on an individual sleeve basis.

3. An offshore structure according to claim 1 in which a substantialnumber of the pile-receiving sleeves are essentially equidistantradially from the mechanical connection means and the pile-guiding meansis the same radial distance from the mechanical connection means.

4. An offshore structure according to claim 1 in which the pile-guidingmeans includes a hollow tube.

5. An offshore structure according to claim 1 having a plurality ofpile-guiding means alignable simultaneously with a plurality ofpile-receiving sleeves.

6. An offshore structure according to claim 1 in which the mechanicalconnection is a universal joint.

7. An offshore structure according to claim 1 in which the mechanicalconnection includes vertical telescoping cylindrical members, one ofwhich is rotatable axially with respect to the other.

8. The method of securing an offshore structure to a sea floor by pileswhich comprises:

positioning the offshore structure in sea floor supporting position,said offshore structure having a base resting on the sea floor, aplurality of substantially hollow vertical pile-receiving sleeves in thebase, an elongated rigid normally substantially vertical member joinedto the base by a mechanical connection means which permits angularpivotal displacement of the vertical member about said connection androtation of the vertical member about the axis of said vertical member,and at least one vertical pile-guiding means positioned on the verticalmember to be axially alignable with a plurality of the pile-receivingsleeves on an individual sleeve basis upon rotation of the verticalmember about its vertical axis; aligning the pile-guiding means with apile-receiving sleeve; feeding a pile along the pile-guiding means intothe aligned pile-receiving sleeve; driving the pile into the sea floor;rotating the vertical member until the pile-guiding means is inalignment with a second pile-receiving sleeve; feeding a pile along thepile-guiding means into the aligned second pile-receiving sleeve;driving the pile into the sea floor; and repeating said method. 9. Themethod of claim 8 in which the pile are driven into the sea floor from aposition on the vertical member above the sea.

1. An offshorE structure adapted to be supported on a sea floor comprising: a base adapted to rest on a sea floor; a plurality of substantially hollow vertical pile-receiving sleeves in the base for receiving piles driven into the sea floor; an elongated rigid normally substantially vertical member joined to the base by a mechanical connection having means for angular pivotal displacement of the vertical member about said connection, said connection having means for rotation of the vertical member about the axis of said vertical member; and the vertical member having at least one vertical pile-guiding means positioned thereon to be axially alignable with a plurality of the vertical pile-receiving sleeves on an individual sleeve basis upon rotation of the vertical member about its vertical axis.
 2. An offshore structure according to claim 1 having index means to align and position the pile-guiding means axially to pile-receiving sleeves on an individual sleeve basis.
 3. An offshore structure according to claim 1 in which a substantial number of the pile-receiving sleeves are essentially equidistant radially from the mechanical connection means and the pile-guiding means is the same radial distance from the mechanical connection means.
 4. An offshore structure according to claim 1 in which the pile-guiding means includes a hollow tube.
 5. An offshore structure according to claim 1 having a plurality of pile-guiding means alignable simultaneously with a plurality of pile-receiving sleeves.
 6. An offshore structure according to claim 1 in which the mechanical connection is a universal joint.
 7. An offshore structure according to claim 1 in which the mechanical connection includes vertical telescoping cylindrical members, one of which is rotatable axially with respect to the other.
 8. The method of securing an offshore structure to a sea floor by piles which comprises: positioning the offshore structure in sea floor supporting position, said offshore structure having a base resting on the sea floor, a plurality of substantially hollow vertical pile-receiving sleeves in the base, an elongated rigid normally substantially vertical member joined to the base by a mechanical connection means which permits angular pivotal displacement of the vertical member about said connection and rotation of the vertical member about the axis of said vertical member, and at least one vertical pile-guiding means positioned on the vertical member to be axially alignable with a plurality of the pile-receiving sleeves on an individual sleeve basis upon rotation of the vertical member about its vertical axis; aligning the pile-guiding means with a pile-receiving sleeve; feeding a pile along the pile-guiding means into the aligned pile-receiving sleeve; driving the pile into the sea floor; rotating the vertical member until the pile-guiding means is in alignment with a second pile-receiving sleeve; feeding a pile along the pile-guiding means into the aligned second pile-receiving sleeve; driving the pile into the sea floor; and repeating said method.
 9. The method of claim 8 in which the pile are driven into the sea floor from a position on the vertical member above the sea. 